1. Field of the Invention
The present invention relates to a rotary connector Attached to a steering apparatus of an automobile or the like and used as respective electric connecting means between electric apparatuses such as a steering heater apparatus and an air bag system provided to a vehicle body and the like.
2. Description of Related Art
Conventionally, there has been proposed a rotary connector for electrically connecting an electric apparatus provided to a steering apparatus such as a steering heater and an electric apparatus provided to a vehicle body.
The rotary connector enables electric connection between an electric apparatus provided to a steering wheel constituting a rotary member and an electric apparatus provided to a vehicle body constituting a fixed member, contains a flexible electric cable or optical fiber cable (hereinafter, these are collectively referred to as xe2x80x9cflexible cablexe2x80x9d) wound in a space in a case constituting a rotor portion (movable side housing) driven to rotate (pivot) by the steering wheel and a stator portion (fixed side housing), and fixes one end thereof to the rotor portion and other end thereof to the stator portion to thereby enable electric connection between the respective electric apparatus by utilizing winding and rewinding the flexible cable.
An explanation will be given of a conventional rotary connector in reference to the drawing.
FIG. 28 is a plane view showing a conventional rotary connector, FIG. 29 is a plane view of an essential portion showing a flexible cable of the conventional rotary connector, FIG. 30 is a side view of the essential portion showing the flexible cable of the conventional rotary connector, FIG. 31 is a plane showing a lead block of the conventional rotary connector, FIG. 32 is a side view showing the lead block of the conventional rotary connector, FIG. 33 is a plane view of an essential portion for explaining attachment of the flexible cable and the lead block of the conventional rotary connector and FIG. 34 is a side view of the essential portions for explaining attachment of the flexible cable and the lead block of the rotary connector.
As shown by FIG. 28, a rotary connector 120 is generally constituted by a fixed side housing 101, a movable side housing 102 rotatably connected to the fixed side housing 101, one sheet of flexible cable 103 constituting a flat cable contained in a space 114 formed between the fixed side and the movable side housings 101 and 102, a moving member 104 pivotably arranged between the fixed side and the movable side housings 101 and 102 and respective single pieces of lead blocks 105 and 106 connected to both ends of the one sheet of the flexible cable 103.
The fixed side housing 101 is provided with an outer cylinder 107 in a cylindrical shape, a bottom wall (not illustrated) in a circular shape provided at an end of the outer cylinder 107 and a hole (not illustrated) in a circular shape provided at a central portion of the bottom wall. Meanwhile, the movable side housing 102 is provided with an inner cylinder 108 in a cylindrical shape and an upper wall (not illustrated) substantially in a circular ring shape provided at one end of the inner cylinder 108, the outer cylinder 107 and the inner cylinder 108 are coaxially arranged and a containing portion 109 in a ring-like shape constituting the space 114 is partitioned between the two outer and inner cylinders 107 and 108.
The moving member 104 is arranged at inside of the containing portion 109 and the moving member 104 is constituted by a rotary plate 110 in a ring-like shape, a group of a plurality of rollers 111 supported on the rotary plate 110 and a pair of fixed columns 112 in a cylindrical shape having circular hollow holes The pair of fixed columns 112 are formed integrally with the rotary plate 110. Further, an opening 113 inserted with one flexible cable 103 is formed between one of the fixed columns 112 and the roller 111.
The flexible cable 103 is pasted with a plurality of (for example, four) of conductors 123 each comprising a copper foil (Cu) or the like in a strip-like shape having a very thin dimension on one face of an insulating film constituting a base film in a strip-like shape and for convenience, the flexible cable 103 is shown in white. An outer end of the flexible cable 103 is electrically and mechanically connected to the lead block 105 constituting a fixed side joint fixed to the outer cylinder 107 and is electrically led out to outside of the fixed side housing 101 via the lead block 105.
Further, an inner end of the flexible cable 103 is electrically and mechanically connected to the lead block 106 constituting a movable side joint-fixed to the inner cylinder 108 and is electrically led out to outside of the movable side housing 102 via the lead block 106.
Next, an explanation will be given of the conventional flexible cable in reference to the drawings.
As shown by FIG. 29 and FIG. 30, the flexible cable 103 in a strip-like shape constituting the flat cable, is provided with a first and a second insulating film 121 and 122 comprising a resin material of, for example, polyethylene terephthalate (PET) or the like, formed in a thin film shape, laminated in two sheets thereof and constituting a long-sizedbase film, and the conductor 123 in the strip-like shape arranged in a state in which a substantially total portion thereof is sandwiched between the first and the second insulating films 121 and 122, and comprising a plurality (for example, four) of copper foils (Cu) respectively formed in an equal width dimension and arranged in parallel at equal intervals.
Further, the respective conductor 123 is provided with a first base conductor 123a a total portion of which is sandwiched between the first and the second insulating films 121 and 122 and a first exposed conductor 123b extended from the first base conductor 123a, exposed from front ends of the first and the second insulating films 121 and 122 and projected outwardly.
Further, one face of the front end of the respective first exposed conductor 123b is pasted with a holding film 124 in a strip-like shape comprising PET or the like for holding a free end side of the respective first exposed conductor 123b. 
Further, such a constitution is provided at both ends of the flexible cable 103.
Further, as shown by FIG. 31 and FIG. 32, the lead block 105 is provided with a base 131 comprising an insulating material and a plurality of first connection terminals 132 arranged to the base 131 by, for example, insert molding.
Further, the base 131 comprises, for example, an insulating synthetic resin material, formed by molding, constituted substantially by a rectangular shape and arranged with a through hole 131a in a rectangular shape substantially at a central portion of the base 131.
Further, a front end side (upper side of FIG. 31) of the base 131 is provided with an inclined base 131b projected outwardly from an upper face of the base 131.
The first connection terminal 132 is provided with a plurality (for example, four) of first connections 132a comprising a flat plate material of a conductive metal such as copper, formed by pressing, having a predetermined width dimension and arranged at equal intervals and first outer terminals 132b extended outwardly from the first connections 132a. The first connection terminal 132 is integrated with the base 131 by being insert-molded into the inclined base 131b of the base 131. The width dimension of the first connection terminal 132 is set to a width dimension substantially the same as the width dimension of the first base conductor 123a and the first exposed conductor 123b of the flexible cable 103.
Under the state, substantially the central portion of the first connection 132a of the first connection terminal 132 is arranged to span over the through hole 131a of the base 131, further, a surface of a rear end side (lower side of FIG. 31) of the first connection 132a and a surface of the base 131 are formed to constitute the same plane.
Next, an explanation will be given of attachment of the flexible cable and the lead block of the conventional rotary connector.
As shown by FIG. 33 and FIG. 34, an upper face of the base 131 of the lead block 105 is laminated and mounted with a side of the flexible cable 103 formed with the first exposed conductor 123b. 
Further, in this state, the respective first connection 132a of the lead block 105 and the respective first exposed conductor 123b of the flexible cable 103 are arranged to laminate opposedly to each other, further, the respective first exposed conductor 123b is arranged above the through hole 131a of the lead block 105.
Further, the respective first connection 132a and the respective laminated first exposed conductor 123b are mechanically and electrically connected by pertinent means such as ultrasonic connecting means.
That is, the respective conductor 123 and the respective first connection terminal.132 are respectively connected individually.
The rotary connector 120 generally constituted in this way is used as electric connecting means of a steering heater apparatus, an air bag system for vehicle mounting, a horn circuit or the like by fixing the fixed side housing 101 to a vehicle body (not illustrated), further, the movable side housing 102 to a steering wheel member (not illustrated) and connecting both ends of the flexible cable 103 to respective electric apparatus on the vehicle side and the steering wheel side via the respective lead blocks 105 and 106 of the fixed side and the movable side.
That is, the rotary connector 120 functions as electric connecting means by respectively making a predetermined current flow in the plurality of respective conductors 123 of the flexible cable 103.
However, although according to the conventional rotary connector 120, the inside of the space 114 formed between the fixed side housing 101 and the movable side housing 102 is contained with the flexible cable 103, since the flexible cable 103 is formed such that the plurality (for example, four) of conductors 123 each comprising the copper foil (Cu) having the very thin dimension in the strip-like shape or the like are pasted on one face of the insulating film, a value of a current which can be made to flow to the respective conductor for the heater apparatus cannot be made so large.
Meanwhile, according to the heater apparatus for steering, in order to make the heater apparatus generate heat, it is requested to supply a comparatively large current value to the heater apparatus and therefore, there is a growing requirement to make the large value of a current flow to the conductor of the flexible cable 103. However, as described above, according to the conventional rotary connector 120, when a large value of a current is made to flow to the conductor of the flexible cable 103, by heat generation by wiring resistance of the conductor, heat is generated excessively and therefore, there is a limit in the current value and accordingly, there poses a problem in supplying a current value sufficient for making the heater apparatus generate heat via the flexible cable
It is an object of the invention to provide a rotary connector capable of making a large current flow to a conductor without increasing lead blocks even when a plurality of flexible cables are used.
According to an aspect of the invention, there is provided a rotary connector comprising a fixed side housing, a movable side housing pivotably mounted to the fixed side housing, a plurality of flexible cables contained in a space formed between the fixed side housing and the movable side housing in a laminated state, and a lead block having a plurality of first connection terminals connected with the plurality of flexible cables, wherein the plurality of flexible cables are constructed by a constitution in which at least one first base conductor in a strip-like shape is sandwiched between insulating films and includes a first exposed conductor constituted by extending and exposing the first base conductor from the insulating films, wherein the first exposed conductors extended from-the respective insulating films at the same position are electrically connected in a state of being laminated to each of the plurality of first connection terminals respectively, and wherein the same current is made to flow to the first base conductors of the plurality of flexible cables.
By such a constitution, there is achieved an effect of capable of providing the rotary connector capable of making a large current flow from the first connection terminal of the lead block to the plurality of first base conductors without increasing the lead blocks.
Further, according to another aspect of the invention, there is provided the rotary connector wherein the first base conductor is used for supplying power for a heater apparatus.
By such a constitution the rotary connector is preferably used particularly for supplying the power having a large current.
Further, according to another aspect of the invention, there is provided the rotary connector wherein the flexible cable is provided with at least one second base conductor for supplying a signal current in parallel with the first base conductor, wherein the lead block is provided with a second connection terminal electrically connected with the second base conductor and the second base conductor, and wherein the second connection terminal are electrically connected.
By such a constitution, there can be provided the rotary connector having multiple functions capable of supplying a current to a heater apparatus or the like and supplying also a current for a signal without increasing the lead blocks since the flexible cable can be provided in parallel with the first and the second base conductors for a plurality of uses.
Further, according to another aspect of the invention, there is provided the rotary connector wherein the first base conductor for supplying power and a plurality of the second base conductors for supplying the signal current are provided separately from each other at areas of the insulating films divided in two.
By such a constitution, the respective base conductors for power supply and for signal are separated and therefore, there can be provided the rotary connector outer connection of which is simple and easy.
Further, according to another aspect of the invention, there is provided the rotary connector wherein a width dimension of the base conductor for supplying power for the heater apparatus is set to a width dimension thicker than a width dimension of the second base conductor for supplying the signal current, and wherein a current capacity of the first base conductor is made larger than a current capacity of the second base conductor.
By such a constitution, a sufficiently large current capacity can be provided by reducing the width of the second base conductor for signal having a comparatively small current and enlarging the width of the first base conductor for power supply.
Further, according to another aspect of the invention, there is provided the rotary connector wherein one of the first connection terminals of the lead blocks includes a plurality of connections connected to each other, and wherein each of the connections is electrically connected with the first exposed conductor.
By such a constitution, by only connecting a plurality of the exposed conductors respectively to the connections, the exposed conductors can be connected in parallel, the current capacity of the exposed conductor can be increased, there can be provided the flexible cable having general purpose performance, further, a terminal number of outside terminals (outside connectors) connected to the lead block can be halved and the total cost can be reduced.
Further, according to another aspect of the invention, there is provided the rotary connector wherein the lead block is provided with a positioning portion comprising a projection, wherein the flexible cable is provided with an engaging portion fitted with the positioning portion, wherein the engaging portion of the flexible cable is fitted to the positioning portion, and wherein the flexible cable is positioned relative to the lead block.
By such a constitution, by positioning the flexible cable to the lead block, attachment of the lead block to the flexible cable can be facilitated and can be carried out inexpensively.
Further, according to another aspect of the invention, there is provided the rotary connector wherein the engaging portion is provided between contiguous ones of the first base conductors among the plurality of first base conductors.
By such a constitution, by the engaging portion provided between the contiguous base conductors, the flexible cable can be positioned relative to the lead block without reducing the width of the base conductor.
Further, according to another aspect of the invention, there is provided a rotary connector comprising a fixed side housing, a movable side housing pivotably mounted to the fixed side housing, at least two flexible cables contained in a space formed between the fixed side housing and the movable side housing in a laminated state, and a lead block having a plurality of first connection terminals connected with at least ones of respective ends of at least the two flexible cables, wherein at least the two flexible cables are constructed by a constitution in which a first base conductor in a strip-like shape is sandwiched between insulating films and include a first exposed conductor exposed from the insulating films and extended from the first base conductor, wherein the first exposed conductors extended from the respective insulating films of at least the two flexible cables at different positions in a width direction of the insulating films, are electrically connected to the respective first connection terminals in a state of being respectively laminated to the plurality of first connection terminals, and wherein the same current is made to flow to the first base conductors of at least the two flexible cables.
By such a constitution, there is achieved an effect of capable of providing the rotary connector capable of making a large current flow to the plurality of first base conductors without increasing the lead blocks.
Further, according to another aspect of the invention, there is provided the rotary connector wherein only one of the first base conductors of the flexible cable is provided to the insulating films by a width dimension more or less narrower than a width dimension of the insulating films.
By such a constitution, only a single piece of the first base conductor is provided by the width dimension more or less narrower than the width dimension of the insulating film and accordingly, the width of the first base conductor on the insulating film can be widened and there is achieved an effect of capable of making a current value capable of being made to flow to the first base conductor sufficiently large.
Further, according to another aspect of the invention, there is provided the rotary connector wherein an even number of sheets equal to or larger than four layers of at least the two flexible cables each formed with only one of the first base conductors are laminated, and wherein the first exposed conductors of the flexible cables of a number of a half of the even number are extended from the insulating films at the same position.
By such a constitution, there is achieved an effect of capable of making the current value capable of being made to flow to the first base conductor further sufficiently large.
Further, according to another aspect of the invention, there is provided the rotary connector wherein an even number of layers equal to or more than four of the flexible cables each formed with only one of the base conductors are laminated.
By such a constitution, there is achieved an effect of capable of making the current value capable of being made to flow to the first base conductor still further sufficiently large.
Further, according to another aspect of the invention, there is provided the rotary connector wherein a plurality of the first base conductors of each of at least the two flexible cables are provided at the insulating films in parallel with each other.
By such a constitution, the flexible cable is applicable to constitutions having multiple functions such as a heater apparatus, a horn apparatus, an air bag system, further, capable of making a large current flow.
Further, according to another aspect of the invention, there is provided the rotary connector wherein the plurality of the first base conductors are provided at the insulating films in parallel with each other, and wherein three layers or more of at least the two of flexible cables are laminated.
By such a constitution, there is achieved an effect of capable of making the current value capable of being made to flow to the first base conductor further sufficiently large.
According to another aspect of the invention, there is provided the rotary connector wherein each of at least the two flexible cables is provided with the first exposed conductor extended from the insulating films at the same position.
By such a constitution, there is achieved an effect of capable of making the current value capable of being made to flow to the first base conductor of each of at least the two flexible cables further sufficiently large.
Further, according to another aspect of the invention, there is provided the rotary connector wherein the first base conductor is used for supplying power for a heater apparatus.
By such a constitution, the rotary connector is preferably used particularly for supplying power having a large current.
Further, according to another aspect of the invention, there is provided the rotary connector wherein each of at least the two flexible cables is provided with a second base conductor for supplying a signal current in parallel with the first base conductor, wherein the lead block is provided with a second connection terminal electrically connected with the second base conductor and the second base conductor, and wherein the second connection terminal are electrically connected.
By such a constitution, there can be provided the rotary connector having multiple functions capable of supplying a current to a heater apparatus or the like and supplying also a signal current without increasing the lead blocks by providing the flexible cable with the first and the second base conductors for a plurality of uses in parallel with each other.
Further, according to another aspect of the invention, there is provided the rotary connector wherein the first connection terminal of the lead block includes a plurality of connections connected to each other, and wherein the respective connections are electrically connected with the first exposed conductors of the flexible cables.
By such a constitution, by only connecting a plurality of pieces of exposed conductors respectively to the connections, the exposed conductors can be connected in parallel, the current capacity of the exposed conductor can be increased, the flexible cable having general purpose performance can be provided, further, a terminal number of outside terminals (outside connectors) connected to the lead block can be halved and the total cost can be reduced.
Further, according to another aspect of the invention, there is provided the rotary connector wherein the lead block is provided with a positioning portion comprising a projection, each of at least the two flexible cables is provided with an engaging portion fitted with the positioning portion, wherein the engaging portion of each of at least the two flexible cables is fitted to the positioning portion, and wherein the flexible cable is positioned relative to the lead block.
By such a constitution, by positioning the flexible cable to the lead block, attachment of the flexible cable to the lead block can be facilitated and can be carried out inexpensively.
Further, according to another aspect of the invention, there is provided the rotary connector wherein a number of a half of a plurality of the flexible cables contained in the space formed between the fixed side housing and the movable side housing in the laminated state are turned back at positions different from each other in a U-like shape and provided in the space to be driven at turn-back positions at which the number of the half of the plurality of flexible cables are separated.
By such a constitution, operation in winding and rewinding the plurality of flexible cables is made smooth.